Device for precision positioning of objects

ABSTRACT

A hydraulically operated link for a hoist comprising a cylinder, a piston therein, a piston rod, a load applying tension to the piston rod and to the opposite end of the cylinder, and a remote control the control being easily operated for allowing flow of fluid to move the piston in the cylinder under conditions of stress; a gauge showing the present pressure, and a pressure operated safety shutoff device for the hoist.

United States Patent 1 i [111 3,73%,4M Fairbanks May ll, R973 54] DEVICE FOR PRECISION 2,945,677 7/1960 Kammerer ..91 47 POSITIONING OF OBJECTS 2,949,894 8/1960 Hewitt [75] Inventor: Roslyn H. Fairbanks, Holden, Mass. 3465649 9/1969 Eggers et [73] Assignee: Inter Continental Corporation, West Primary Examiner-Ev0n C. Blunk Boylston, Mass. Assistant ExaminerMerle F. Mafiei [22] Filed: Jam 11, 1971 AttorneyCharles R. Fay

App]. No.2 105,489

US. Cl. ..254/167, 91/47, 91/462 Int. Cl. ..B66d 1/00 Field of Search ..254/150 PH, 167,

References Cited UNITED STATES PATENTS 1/1907 Miller ..9 1/462 X 7 ABSTRACT A hydraulically operated link for a hoist comprising a cylinder, a piston therein, a piston rod, a load applying tension to the piston rod and to the opposite end of the cylinder, and a remote control the control being easily operated for allowing flow of fluid to move the piston in thecylinder under conditions of stress; a gauge showing the present pressure, and a pressure operated safety shutoff device for the hoist.

4 Claims, 2 Drawing Figures PATENTEWY Hm Y 3,730,484

ROSLYN H. FAIRBANKS r BY 4% 2%.

ATTORNEY BACKGROUND OF THE INVENTION In the past, objects such as heavy workpieces have been generally easily moved from one place to another in a factory by means of hoists, or mobile lifters of one kind or another, etc., but these devices are not provided with means for precision positioning of the ohhoist of well known description generally indicated at 12. This hoist is usually provided with a hook i4 and the link which comprises the present invention generally indicated at 16 is connected to the hook by means of an end ring, hook, etc., 18. The opposite end of cylinder 16 is provided with another ring, hook or the like 20 which is connected to a sling 22, the sling jects, and therefore they are often damaged and must 1 be precisely located by hand.

It is the general object of the present invention to provide a simple inexpensive device which can be usedv safely with a hoist, mobile lifter, etc., and which can easily be controlled by an operator at any position, to precision position the object in extremely small increments exactly where desired without any injury, dropping, etc.

SUMMARY OF THE INVENTION A relatively simple hydraulic cylinder is provided having a piston and piston rod, the piston rod extending out one end thereof and terminating in a device for attachment to any kind of lifter or workpiece as for instance by means of an eye or a hook. A fixed similar device is located at the opposite end of the cylinder. A manual remote control valve allows for passage of fluid from one side of the piston to the other side thereof when desired, to cause the piston rod to be carried out through the end of the cylinder to position an object which is attached thereto. The fixed ring or book is provided for attaching to the hoist hook or to the lifter arm of any kind of lifting mechanism, thus applying stress to the fluid in the cylinder when the object is lifted.

The device should be limited to a predetermined pressure, and since this is determined by the load, a pressure gauge is provided to indicate at all times the working pressure in the device, and a hoist cut-off switch operated at a predetermined pressure is used to stop the lift when a load is too great.

It will be seen that with an object being lifted or lowered with the cylinder acting as a link between the hoist and the object, pressure is exerted in a direction to move the piston so that the piston rod will extend further from the cylinder, but this cannot be done unless the valve is opened. The valve is of simple nature and is quickly and easily operated so that the motion of the piston rod and therefore of the object is an increment of extremely small size if this should be desired, or up to several inches, if necessary.

If desired, springs can be used to return the piston to its original position, or it can simply be pushed in with the provisions of well known types of check valves, so that the fluid will flow from one side of the piston to the other for reuse of the provision positioning link mechanism described.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the device in operation, and

FIG. 2 is a longitudinal sectional view therethrough.

PREFERRED EMBODIMENT OF THE INVENTION FIG. 1 illustrates a workpiece W which is to be positioned on a platfonn, table or the like by means of a being secured with respect to workpiece W in order to position the same by means of the hoist.

There is a valve operating knob 26 and by this control means the workpiece W may be lifted and dropped in extremely fine increments so as to position it on the table 10 without any damage, or any muscle power being necessary as by additional operators who are generally used to push or 'pull the workpiece W so that the operator of the hoist can then drop it where it is wanted.

The details of the device are illustrated in FIG. 2. As shown the cylinder 16 comprises a cylindrical member having a pair of end caps as at 30 and 32. Cap 32 carries the ring 20 and the ring 18 is secured to the external end 34 of a piston rod 36 attached to a piston 38.

The end caps may be secured in position by any desired or convenient means and sealed as at 40 are provided for the usual reasons. The valve operating means 26 opens and closes a valve 42 for a passage 44 by rotation or push-pull depending on the type of valve used. When the valve 42 is open, fluid flows into a passage 46 in end cap 32 leading into the side of piston 38 which is indicated at 48, opposite to piston rod 36. The piston 38 also has check valves 50 which allow fluid at end 48 of the piston to move reversely into the interior of the cylinder 16 under conditions of end pressure exerted inwardly on the end of the cylinder and on the piston rod, when the device is idle.

With the parts as shown in FIG. 2 and one ring or the other 18 or 20 being suspended for instance as shown in FIG. 1, and a heavy workpiece being attached to the other ring, it will be seen that pressure is exerted thereby to tend to move piston 38 and pistonrod 36 and thereby ring 18 to the left. However this is impossible because the cylinder is full of fluid and the valve 42 is closed. However by mere simple partial twist (or pull) of control 26 the passage at 44 is open to the piston end 48, and therefore the piston and rod will proceed as indicated until such time as the operator closes the valve once more. The fingerpiece 26 can be used to crack the valve only fora very minute increment of travel of the piston.

By this means, a heavy object such as illustrated in FIG. 1 is enabled to be moved in extremely minute increments and can therefore gently position large heavy workpieces, etc., where desired.

When it is desired to reposition the piston, pressure is merely exerted inwardly on the piston rod, and the check valves operate to allow passage of the fluid back to the other side of the piston. Alternatively either ex-.

be utilized in an upright position and any kind of pushpull device ofany convenient kind illustrated at 52-may be utilized to be push-pulled by the covered flexible rod 54 from any remote position desired. This is not shown in FIG. 1 but is alternative construction.

However it is preferred that a pressure gauge 56 of commercial design should be applied to the casing 16 as by a fitting 58 or the like to register the pressure in the chamber. This pressure will be dictated by the weight of the load and if the particular link positioner is designed for say 4,000 pounds, and the pressure on the dial exceeds 4,000 pounds, the operator will be appraised of the fact that the weight is too heavy and that he must therefore use a larger or an additional link positioner.

Also directly communicating with the chamber in the device 16 there may be provided a pressure actuated safety switch 60 of any convenient commercial type controlling the motor of the hoist 12. This pressure safety device is utilized to shut the motor off when the weighted capacity of the lifter is reached. For instance, if the capacity is 4,000 pounds, then at anything over 4,000 pounds the pressure will be such as to actuate the pressure switch to shut off the motor.

It will be seen therefore that the lifting device presented is extremely versatile. It can be used closely controlled by the operator as shown in FIG. 1 or can be used as well by an operator at a remote distance. If the safety device 60 should not be used, still the operator will be appraised by the pressure gauge 56 that he may be exceeding the rated capacity of the device, and if the safety device 60 is used, then excess pressure automatically shuts off the motor of the hoist 12.

I claim:

l. The combination with a motor-operated lifting mechanism, of a link, said link being attached to the lifting mechanism for raising and lowering of the link, said link comprising a generally closed upright cylinder, a piston and fluid in the cylinder, a piston rod on the piston extending out through the lower end of the cylinder, and a normally closed valve for controlling flow of fluid from the lower side of the piston to the top side thereof, the piston normally being fixed relative to the cylinder when the lifting mechanism is being operated, the link thereby being inoperative when the lifting mechanism is operated, but when tension is applied to the extending end of the piston rod, the valve upon being selectively opened provides a passage for fluid below the piston and thus under pressure to flow to the opposite upper side of the piston, allowing the piston rod to move in a direction downwardly and outwardly of the cylinder, and means on the outwardly extending part of the piston to carry an object to be precisely positioned, said link and cylinder being entirely self-contained, the piston being movable reversely only by non-hydraulic means.

2. The combination of claim 1 including a safety switch for the motor of the lifting mechanism, said safety switch being pressure operated, and means connected to the cylinder and the switch to operate the switch at a predetermined pressure in the cylinder.

3. The combination of claim 2 including means mounting the switch on the cylinder.

4. The combination of claim 1 including a remote distance. 

1. The combination with a motor-operated lifting mechanism, of a link, said link being attached to the lifting mechanism for raising and lowering of the link, said link comprising a generally closed upright cylinder, a piston and fluid in the cylinder, a piston rod on the piston extending out through the lower end of the cylinder, and a normally closed valve for controlling flow of fluid from the lower side of the piston to the top side thereof, the piston normally being fixed relative to the cylinder when the lifting mechanism is being operated, the link thereby being inoperative when the lifting mechanism is operated, but when tension is applied to the extending end of the piston rod, the valve upon being selectively opened provides a passage for fluid below the piston and thus under pressure to flow to the opposite upper side of the piston, allowing the piston rod to move in a direction downwardly and outwardly of the cylinder, and means on the outwardly extending part of the piston to carry an object to be precisely positioned, said link and cylinder being entirely self-contained, the piston being movable reversely only by non-hydraulic means.
 2. The combination of claim 1 including a safety switch for the motor of the lifting mechanism, said safety switch being pressure operated, and means connected to the cylinder and the switch to operate the switch at a predetermined pressure in the cylinder.
 3. The combination of claim 2 including means mounting the switch on the cylinder.
 4. The combination of claim 1 including a remote control for the valve comprising a flexible cable connected thereto for direct control thereof from a distance. 